High pressure RF-DC sputtering and methods to improve film uniformity and step-coverage of this process

ABSTRACT

Embodiments of the invention generally provide a processing chamber used to perform a physical vapor deposition (PVD) process and methods of depositing multi-compositional films. The processing chamber may include: an improved RF feed configuration to reduce any standing wave effects; an improved magnetron design to enhance RF plasma uniformity, deposited film composition and thickness uniformity; an improved substrate biasing configuration to improve process control; and an improved process kit design to improve RF field uniformity near the critical surfaces of the substrate. The method includes forming a plasma in a processing region of a chamber using an RF supply coupled to a multi-compositional target, translating a magnetron relative to the multi-compositional target, wherein the magnetron is positioned in a first position relative to a center point of the multi-compositional target while the magnetron is translating and the plasma is formed, and depositing a multi-compositional film on a substrate in the chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 12/754,473, filed on Apr. 5, 2010, which claimsbenefit of U.S. Provisional Patent Application Ser. No. 61/166,682,filed Apr. 3, 2009, and U.S. Provisional Patent Application Ser. No.61/319,377, filed Mar. 31, 2010, which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

Embodiments of the present invention generally relate to methods and anapparatus of forming metal and dielectric layers. More particularly,embodiments of the invention relate to methods and an apparatus forforming a metal gate and associated dielectric layers.

DESCRIPTION OF THE RELATED ART

Integrated circuits may include more than one million micro-electronicdevices such as transistors, capacitors, and resistors. One type ofintegrated circuit are field effect transistors (e.g., complementarymetal-oxide-semiconductor (CMOS) field effect transistors) that areformed on a substrate (e.g., semiconductor substrate) and cooperate toperform various functions within the circuit. A CMOS transistorcomprises a gate structure disposed between source and drain regionsthat are formed in the substrate. The gate structure generally comprisesa gate electrode and a gate dielectric. The gate electrode is disposedover the gate dielectric to control a flow of charge carriers in achannel region formed between the drain and source regions beneath thegate dielectric. To increase the speed of the transistor, the gatedielectric may be formed from a material having a dielectric constantgreater than 4.0. Herein such dielectric materials are referred to ashigh-k materials.

The gate dielectric layer may be formed of dielectric materials such assilicon dioxide (SiO₂), or a high-k dielectric material having adielectric constant greater than 4.0, such as SiON, SiN, hafnium oxide(HfO₂), hafnium silicate (HfSiO₂), hafnium silicon oxynitride (HfSiON),zirconium oxide (ZrO₂), zirconium silicate (ZrSiO₂), barium strontiumtitanate (BaSrTiO₃, or BST), lead zirconate titanate (Pb(ZrTi)O₃, orPZT), and the like. It should be noted, however, that the film stack maycomprise layers formed of other materials.

Gate stacks may also incorporate metal layers formed on the high-kdielectric instead of conventional polysilicon. The metal layers mayinclude TiN, TiAl, WN, HfC, HfN, silicides for FUSI or fully silicidedmetal gates.

Further, a high mobility interface layer may be deposited in the gatestructure between the substrate and the high-k dielectric layer. Variousmethods may be used to form CMOS high-k/metal gate stack structures suchas a replacement gate approach, a gate first approach, and a gate lastapproach.

Fabrication of gate structures of field effect transistors having thehigh-k gate dielectric/gate last approach comprises a series ofprocessing steps (e.g., depositing multiple layers). In a gate stackstructure forming process, not only conformal films are required, butalso the good qualities of the interfacial layers between each layer areessential.

In conventional CMOS fabrication schemes, the substrate is required topass between tools having the various reactors coupled thereto. Theprocess of passing the substrate between tools necessitates the removalof the substrate from the vacuum environment of one tool for transfer atambient pressures to the vacuum environment of a second tool. In theambient environment, the substrates are exposed to mechanical andchemical contaminants, such as particles, moisture, and the like, thatmay damage the gate structures being fabricated and possibly form anundesired interfacial layer, e.g., native oxide, between each layerwhile transferring. As gate structures become smaller and/or thinner toincrease the device speed, the detrimental effect of forming interfaciallayers or contamination becomes an increased concern. Additionally, thetime spent on transferring the substrate between the cluster toolsdecreases productivity in manufacture of the field effect transistors.

Additionally, fabrication processes for gate stack structures mayinclude a chemical vapor deposition (CVD) process to form the metallayers. However, residual particles from organo-metallic precursors maycontaminate the underlying dielectric layers when forming the metalportion of the gate stack, adversely affecting the dielectric propertiesof the gate dielectric layer. Furthermore, as transistor sizes decreasebelow 45 nm and have higher aspect ratios, achieving sufficient filmuniformity and step-coverage becomes increasingly difficult.

Therefore, there is a need in the art for methods and an apparatus forforming a gate stack that has improved properties.

SUMMARY OF THE INVENTION

In one embodiment of the invention, a high pressure RF DC PVD chamber isdisclosed having a dual ring magnetron comprising asymmetric magnetrings, a low profile cover ring and deposition ring, and a pedestalcapacitive tuner.

In another embodiment of the invention, a method for depositing a metalfilm is disclosed. The method includes flowing a high pressure gas intoa chamber, igniting a plasma from the gas using an RF and DC powersource electrically connected to a sputtering target, forming a denseplasma by using a magnetron, tuning a pedestal to match the RF powersource, and depositing a metal film on a substrate in the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a cross-sectional view of a chamber according to oneembodiment of the invention.

FIG. 1B depicts an isometric view of a chamber according to oneembodiment of the invention.

FIG. 2 is a close-up cross-sectional view of a portion of the chamberillustrated in FIG. 1A according to one embodiment of the invention.

FIG. 3A is a close-up cross-sectional view of a portion of the chamberillustrated in FIG. 1A according to one embodiment of the invention.

FIG. 3B is a top view of a portion of the chamber illustrated in FIG. 1Aaccording to one embodiment of the invention.

FIG. 3C is a top view of a portion of the chamber illustrated in FIG. 1Aaccording to one embodiment of the invention.

FIG. 4A is an isometric view of a magnetron viewed from the target sideaccording to one embodiment of the invention.

FIG. 4B is a bottom view of a portion of the magnetron according to oneembodiment of the invention.

FIG. 4C is a bottom view of a portion of the magnetron according to oneembodiment of the invention.

FIG. 4D is a bottom view of a portion of the magnetron according to oneembodiment of the invention.

FIG. 4E is a top view of a portion of the magnetron according to oneembodiment of the invention.

FIG. 5A is a cross-sectional view of a portion of a process kitaccording to one embodiment of the invention.

FIG. 5B is a cross-sectional view of a portion of a conventional processkit.

FIG. 6 is a schematic view of an impedance controller according to oneembodiment of the invention.

FIGS. 7A-7H depict a schematic cross section of an example of a processfor forming a CMOS type integrated circuit.

FIG. 8 illustrates elastic collisions of particles during a sputteringprocess.

FIG. 9 illustrates the sputtering distribution of a multi-componenttarget in a sputtering chamber.

FIGS. 10A-10C illustrate the erosion tracks formed in a sputteringtarget during processing.

FIG. 11 illustrates a process diagram of the method of depositing a filmaccording to one embodiment of the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the invention generally provide a processing chamber usedto perform a physical vapor deposition (PVD) process. In one embodiment,the process chamber design is adapted to deposit a desired materialusing an RF physical vapor deposition (PVD) process. The processingchamber disclosed herein may be especially useful for depositingmulti-compositional films. The processing chamber's design features mayinclude: an improved RF feed configuration to reduce any standing waveeffects; an improved magnetron design to enhance RF plasma uniformity,deposited film composition and thickness uniformity; an improvedsubstrate biasing configuration to improve process control; and animproved process kit design to improve RF field uniformity near thecritical surfaces of the substrate to promote greater process uniformityand repeatability.

FIG. 1A illustrates an exemplary semiconductor processing chamber 100having an upper process assembly 108, a process kit 150 and a pedestalassembly 120, which are all configured to process a substrate 105disposed in a processing region 110. The process kit 150 includes aone-piece grounded shield 160, a lower process kit 165, and an isolatorring assembly 180. In the version shown, the processing chamber 100comprises a sputtering chamber, also called a physical vapor depositionor PVD chamber, capable of depositing a single or multi-compositionalmaterial from a target 132 on the substrate 105. The processing chamber100 may also be used to deposit aluminum, copper, nickel, platinum,hafnium, silver, chrome, gold, molybdenum, silicon, ruthenium, tantalum,tantalum nitride, tantalum carbide, titanium nitride, tungsten, tungstennitride, lanthanum, alumina, lanthanum oxides, nickel platinum alloys,and titanium, and or combination thereof. Such processing chambers areavailable from Applied Materials located in Santa Clara, Calif. It iscontemplated that other processing chambers including those from othermanufacturers may be adapted to benefit from one or more of theembodiments of the invention described herein.

The processing chamber 100 includes a chamber body 101 having sidewalls104, a bottom wall 106, and an upper process assembly 108 that enclose aprocessing region 110 or plasma zone. The chamber body 101 is typicallyfabricated from welded plates of stainless steel or a unitary block ofaluminum. In one embodiment, the sidewalls comprise aluminum and thebottom wall comprises stainless steel plate. The sidewalls 104 generallycontain a slit valve (not shown) to provide for entry and egress of asubstrate 105 from the processing chamber 100. Components in the upperprocess assembly 108 of the processing chamber 100 in cooperation withthe grounded shield 160, pedestal assembly 120 and cover ring 170confine the plasma formed in the processing region 110 to the regionabove the substrate 105.

A pedestal assembly 120 is supported from the bottom wall 106 of thechamber 100. The pedestal assembly 120 supports a deposition ring 502along with the substrate 105 during processing. The pedestal assembly120 is coupled to the bottom wall 106 of the chamber 100 by a liftmechanism 122, which is configured to move the pedestal assembly 120between an upper processing position and lower transfer position.Additionally, in the lower transfer position, lift pins 123 are movedthrough the pedestal assembly 120 to position the substrate a distancefrom the pedestal assembly 120 to facilitate the exchange of thesubstrate with a substrate transfer mechanism disposed exterior to theprocessing chamber 100, such as a single blade robot (not shown). Abellows 124 is typically disposed between the pedestal assembly 120 andthe chamber bottom wall 106 to isolate the processing region 110 fromthe interior of the pedestal assembly 120 and the exterior of thechamber.

The pedestal assembly 120 generally includes a support 126 sealinglycoupled to a platform housing 128. The platform housing 128 is typicallyfabricated from a metallic material such as stainless steel or aluminum.A cooling plate (not shown) is generally disposed within the platformhousing 128 to thermally regulate the support 126. One pedestal assembly120 that may be adapted to benefit from the embodiments described hereinis described in U.S. Pat. No. 5,507,499, issued Apr. 16, 1996 toDavenport et al. which is incorporated herein by reference in itsentirety.

The support 126 may be comprised of aluminum or ceramic. The substratesupport 126 has a substrate receiving surface 127 that receives andsupports the substrate 105 during processing, the substrate receivingsurface 127 being substantially parallel to a sputtering surface 133 ofthe target 132. The support 126 also has a peripheral edge 129 thatterminates before an overhanging edge 105A of the substrate 105. Thesupport 126 may be an electrostatic chuck, a ceramic body, a heater or acombination thereof. In one embodiment, the support 126 is anelectrostatic chuck that includes a dielectric body having a conductivelayer, or electrode 126A, embedded therein. The dielectric body istypically fabricated from a high thermal conductivity dielectricmaterial such as pyrolytic boron nitride, aluminum nitride, siliconnitride, alumina or an equivalent material. Other aspects of thepedestal assembly 120 and support 126 are further described below. Inone embodiment, the conductive layer 126A is configured so that when aDC voltage is applied to the conductive layer 126A, by an electrostaticchuck power supply 143, a substrate 105 disposed on the substratereceiving surface 127 will be electrostatically chucked thereto toimprove the heat transfer between the substrate 105 and the support 126.In another embodiment, an impedance controller 141 is also coupled tothe conductive layer 126A so that a voltage can be maintained on thesubstrate during processing to affect the plasma interaction with thesurface of the substrate 105.

The chamber 100 is controlled by a system controller 190 that isgenerally designed to facilitate the control and automation of theprocessing chamber 100 and typically includes a central processing unit(CPU) (not shown), memory (not shown), and support circuits (or I/O)(not shown). The CPU may be one of any form of computer processors thatare used in industrial settings for controlling various systemfunctions, substrate movement, chamber processes, and support hardware(e.g., sensors, robots, motors, etc.), and monitor the processes (e.g.,substrate support temperature, power supply variables, chamber processtime, I/O signals, etc.). The memory is connected to the CPU, and may beone or more of a readily available memory, such as random access memory(RAM), read only memory (ROM), floppy disk, hard disk, or any other formof digital storage, local or remote. Software instructions and data canbe coded and stored within the memory for instructing the CPU. Thesupport circuits are also connected to the CPU for supporting theprocessor in a conventional manner. The support circuits may includecache, power supplies, clock circuits, input/output circuitry,subsystems, and the like. A program (or computer instructions) readableby the system controller 190 determines which tasks are performable on asubstrate. Preferably, the program is software readable by the systemcontroller 190 that includes code to perform tasks relating tomonitoring, execution and control of the movement and various processrecipe tasks and recipe steps being performed in the processing chamber100. For example, the controller 190 can comprise program code thatincludes a substrate positioning instruction set to operate the pedestalassembly 120; a gas flow control instruction set to operate gas flowcontrol valves to set a flow of sputtering gas to the chamber 100; a gaspressure control instruction set to operate a throttle valve or gatevalve to maintain a pressure in the chamber 100; a temperature controlinstruction set to control a temperature control system (not shown) inthe pedestal assembly 120 or sidewalls 104 to set temperatures of thesubstrate or sidewalls 104, respectively; and a process monitoringinstruction set to monitor the process in the chamber 100.

The chamber 100 also contains a process kit 150 which comprises variouscomponents that can be easily removed from the chamber 100, for example,to clean sputtering deposits off the component surfaces, replace orrepair eroded components, or to adapt the chamber 100 for otherprocesses. In one embodiment, the process kit 150 comprises an isolatorring assembly 180, a grounded shield 160 and a ring assembly 168 forplacement about a peripheral edge 129 of the support 126 that terminatesbefore an overhanging edge of the substrate 105.

FIG. 1B is an isometric view of the processing chamber 100 that iscoupled to a processing position of a cluster tool 103. The cluster tool103 may also contain other processing chambers (not shown) that areadapted to perform one or more processing steps on a substrate prior toor after performing the deposition process in the processing chamber100. An exemplary cluster tool 103 may include a Centura™ or an Endura™systems available from Applied Materials, Santa Clara, Calif. Thecluster tool 103 may include one or more load-lock chambers (not shown),one or more process chambers, and a cool-down chamber (not shown), allof which are attached to a central transfer chamber 103A. In oneexample, the cluster tool 103 may have processing chambers that areconfigured to perform a number of substrate processing operations suchas cyclical layer deposition, chemical vapor deposition (CVD), physicalvapor deposition (PVD), atomic layer deposition (ALD), etch, pre-clean,degas, anneal, orientation and other substrate processes. A transfertool, for example, a robot (not shown) disposed in the transfer chamber103A, may be used to transfer substrates to and from one or morechambers attached to the cluster tool 103.

With reference to FIGS. 1A and 2, in one embodiment, the process chamber100 includes an isolator ring assembly 180 that includes an isolatorring 250 and support ring 267 that are disposed adjacent to the target132, the edge 216 of the grounded shield 160 and target isolator 136.The isolator ring 250 extends about and surrounds the outer edge of thesputtering surface 133 of the target 132. The isolator ring 250 of theisolator ring assembly 180 comprises a top wall 252, a bottom wall 254,and a support rim 256 that extends radially outward from the top wall252 of the isolator ring 250. An example of an exemplary isolator ringdesign is further described in the commonly assigned U.S. patentapplication Ser. No. 12/433,315, which is herein incorporated byreference.

The top wall 252 comprises an inner periphery 258, a top surface 260positioned adjacent to the target 132, and an outer periphery 262positioned adjacent to the target isolator 136. The support rim 256comprises a bottom contact surface 264 and an upper surface 266. Thebottom contact surface 264 of the support rim 256 is supported by aspring member 267A (e.g., compressible metal spring element) that iscoupled to the support ring 267 to bias the isolator ring towards andagainst the surface of the target isolator 136. The use of the springmember 267A can help reduce the tolerance stack-up between the isolatorring 250, and its supporting components, and the sputtering surface 133so that a desirable gap can be reliably maintained between the topsurface 260 of the isolator ring 250 and the sputtering surface 133. Thegap formed between the top surface 260 and the sputtering surface 133 isimportant to prevent the plasma formed in the processing region 110 fromextending into the gap, and causing sealing and/or particle problems tooccur. The bottom wall 254 comprises an inner periphery 268, an outerperiphery 270, and a bottom surface 272. The inner periphery 268 of thebottom wall 254 and the inner periphery 258 of the top wall 252 form aunitary surface.

A vertical trench 276 is formed at a transition point 278 between theouter periphery 270 of the bottom wall 254 and the bottom contactsurface 264 of the support rim 256. The step 221 of the shield 160 incombination with the vertical trench 276 provides a labyrinth gap thatprevents conductive material from creating a surface bridge between theisolator ring assembly 180 and the shield 160, thus maintainingelectrical discontinuity while still providing shielding to the chamberwalls 104, 106. In one embodiment, the isolator ring assembly 180provides a gap between the target 132 and the ground components of theprocess kit 150 while still providing shielding to the chamber walls.The stepped design of the isolator ring assembly 180 allows for theshield 160 to be centered with respect to the adapter 220, which is alsothe mounting point for the mating shields and the alignment features forthe target 132. The stepped design also eliminates line-of-sitedeposition from the target 132 to the support ring 267, eliminatingarcing concerns in this area.

In one embodiment, the isolator ring assembly 180 has a grit-blastedsurface texture or arc sprayed aluminum film deposited thereon toachieve a surface roughness (Ra value) of at least 180±20 microinches(0.0041-0.0051 mm) to enhance film adherence. The support rim 256 allowsfor the isolator ring assembly 180 to be centered with respect to theadapter 220 while eliminating the line-of-site from the target 132 tothe grounded shield 160 thus eliminating stray plasma concerns. In oneembodiment the support ring 267 comprises a series of alignment pins(not shown) that locate/align with a series of slots (not shown) in theshield 160.

The inner surface 214 of the shield 160 generally encircles thesputtering surface 133 of a sputtering target 132 that faces the support126 and the peripheral edge 129 of the support 126. The shield 160covers and shadows the sidewalls 104 of the chamber 100 to reducedeposition of sputtering deposits originating from the sputteringsurface 133 of the sputtering target 132 onto the components andsurfaces behind the shield 160. For example, the shield 160 can protectthe surfaces of the support 126, the overhanging edge of the substrate105, sidewalls 104 and bottom wall 106 of the chamber 100.

Lid Assembly Region

The upper process assembly 108 may also comprise an RF source 181, adirect current (DC) source 182, an adaptor 102, a motor 193, and a lidassembly 130. The lid assembly 130 generally comprises a target 132, amagnetron system 189 and a lid enclosure 191. The upper process assembly108 is supported by the sidewalls 104 when in a closed position, asshown in FIGS. 1A and 1B. A ceramic target isolator 136 is disposedbetween the isolator ring assembly 180, the target 132 and adaptor 102of the lid assembly 130 to prevent vacuum leakage therebetween. Theadaptor 102 is sealably coupled to the sidewalls 104, and is configuredto help with the removal of the upper process assembly 108 and isolatorring assembly 180.

When in the processing position, the target 132 is disposed adjacent tothe adaptor 102, and is exposed to the processing region 110 of theprocessing chamber 100. The target 132 contains material that isdeposited on the substrate 105 during a PVD, or sputtering, process. Theisolator ring assembly 180 is disposed between the target 132 and theshield 160 and chamber body 101 to electrically isolate the target 132from the shield 160 and chamber body 101.

During processing, the target 132 is biased relative to a groundedregion of the processing chamber (e.g., chamber body 101 and adaptor102) by a power source disposed in the RF source 181 and/or the directcurrent (DC) source 182. It is believed that by delivering RF energy andDC power to the target 132 during a high pressure PVD process,significant process advantages can be achieved over conventional lowpressure DC plasma processing techniques when used in conjunction withsputtering a multi-compositional film, such as sputtering titanium andaluminum, or titanium and tungsten to name just a few. Additionally, inone embodiment, the combination of RF and DC power sources allows for alower overall RF power to be used during processing versus a RF onlysource, which can help to decrease plasma related damage of thesubstrate and increase device yield. In one embodiment, the RF source181 comprises an RF power source 181A and an RF match 181B that areconfigured to efficiently deliver RF energy to the target 132. In oneexample, the RF power source 181A is capable of generating RF currentsat a frequency of between about 13.56 MHz and about 128 MHz at powersbetween about 0 and about 5 kWatts. In one example, the DC power supply182A in the DC source 182 is capable of delivering between about 0 andabout 10 kWatts of DC power. In another example, the RF power source181A is capable of generating an RF power density of between about 0 andabout 33 kWatts/m² at the target and the DC source 182 is capable ofdelivering a power density of between about 0 and about 66 kWatts/m².

During processing, a gas, such as argon, is supplied to the processingregion 110 from a gas source 142 via conduits 144. The gas source 142may comprise a non-reactive gas such as argon, krypton, helium or xenon,which is capable of energetically impinging upon and sputtering materialfrom the target 132. The gas source 142 may also include a reactive gas,such as one or more of an oxygen-containing gas or a nitrogen-containinggas, which is capable of reacting with the sputtering material to form alayer on a substrate. Spent process gas and byproducts are exhaustedfrom the chamber 100 through exhaust ports 146 that receive spentprocess gas and direct the spent process gas to an exhaust conduit 148having an adjustable position gate valve 147 to control the pressure inthe processing region 110 in the chamber 100. The exhaust conduit 148 isconnected to one or more exhaust pump 149, such as a cryopump.Typically, the pressure of the sputtering gas in the chamber 100 duringprocessing is set to sub-atmospheric levels, such as a vacuumenvironment, for example, a pressure of about 0.6 mTorr to about 400mTorr. In one embodiment, the processing pressure is set to about 20mTorr to about 100 mTorr. A plasma is formed between the substrate 105and the target 132 from the gas. Ions within the plasma are acceleratedtoward the target 132 and cause material to become dislodged from thetarget 132. The dislodged target material is deposited on the substrate.

Referring to FIG. 3A, the lid enclosure 191 generally comprises aconductive wall 185, a center feed 184 and shielding 186 (FIGS. 1A and1B). In this configuration, the conductive wall 185, the center feed184, the target 132 and a portion of the motor 193 enclose and form aback region 134. The back region 134 is a sealed region disposed on theback side of the target 132 and is generally filled with a flowingliquid during processing to remove the heat generated at the target 132during processing. In one embodiment, the conductive wall 185 and centerfeed 184 are configured to support the motor 193 and magnetron system189, so that the motor 193 can rotate the magnetron system 189 duringprocessing. In one embodiment the motor 193 is electrically isolatedfrom the RF or DC power delivered from the power supplies by use of adielectric layer 193B, such as Delrin, G10, or Ardel.

The shielding 186 may comprise one or more dielectric materials that arepositioned to enclose and prevent the RF energy delivered to the target132 from interfering with and affecting other processing chambersdisposed in the cluster tool 103 (FIG. 1B). In one configuration, theshielding 186 may comprise a Delrin, G10, Ardel or other similarmaterial and/or a thin grounded sheet metal RF shield.

Power Deliver

In one embodiment, as illustrated in FIG. 1A, during processing thecapacitively coupled target 132 is powered during plasma processingusing RF or VHF energy to ionize and dissociate a processing gas nearthe sputtering surface 133 of the target 132 so that the ionized gaswill sputter material from the biased target. However, as processingchamber sizes grow to process 300 mm and larger substrates, due tofinite reactor dimensions and boundary conditions on the electrodes, thegenerated RF fields can inherently form standing waves in the processingregion 110 at typical RF and VHF frequencies. If the size of theelectrodes becomes comparable with the excitation wavelengths,electromagnetic effects created by the formed standing wave can causenon-uniformities in plasma and the deposited film on the substrate. Thestanding waves and plasma non-uniformities have a strong influence onthe thickness and properties of thin films deposited by PVD reactors oron the process uniformity in plasma processing chambers in general.Non-uniform films may lead to center-to-edge and edge-to-edgenon-uniformities, which in some cases may lead to non-functioningdevices.

In some cases, the standing wave effects and related plasmanon-uniformities may be improved to an extent by shaping the electrodes(e.g., PVD target), lowering the RF frequencies, and tuning theprocessing parameters, such as chamber pressure, and/or combinationsthereof. However, when as the processing chamber size increases toreflect the demand for larger substrates, simply scaling up theaforementioned countermeasures to the standing wave effect and plasmanon-uniformities may not be sufficient and/or lead to non-ideal plasmaprocessing conditions.

It is believed that these non-uniformities can be further induced andexacerbated as the processing pressures are increased and by thenon-symmetric delivery of RF power to the electrode. The non-symmetricdelivery of RF power causes an uneven spread of the delivered RF powerto the electrode that creates plasma non-uniformity. FIG. 3B is aschematic top view of a target 132 that schematically illustrates theflow of RF power delivered from an asymmetrically positioned powerdelivery point “F” across the target surface. As shown, the RF powerdelivery point “F” is offset from the center “M” of the target 132 by adistance “O”. In this configuration, the current flow emanating from thepower delivery point “F” is non-uniform since it will flow differentdistances to spread across the surface of the target, for example, asschematically illustrated by the current flow in opposing directions C₁₂and C₁₁ that have different path lengths in order to reach the edge ofthe target 132. It is believed that the uneven flow will setupnon-symmetric standing waves in the processing region 110, which willcause plasma and deposition non-uniformity.

In one embodiment, as illustrated in FIGS. 3A and 3C, the RF power isdelivered to a center feed 184 that is positioned at the center “M”, orcenter axis, of the target 132. In this configuration, the RF energydelivered from the RF power source 181A disposed in the RF source 181 isconfigured to flow through the center feed 184 and the conductive wall185 to the target 132 during processing. In one embodiment, as shown inFIGS. 3A and 3C, the center feed 184 is axially symmetric about thecenter “M” of the target 132. In one embodiment, the aspect ratio of thecenter feed 184 is configured so that the delivery of RF energy at oneedge of the upper surface 184A of the center feed 184, as shown in FIG.3A, will allow the uniform delivery of RF energy to the conductive wall185 and/or target 132 at the lower surface 184B of the center feed 184.The RF current generally flows along the path shown by arrows “C” inFIG. 3A. In this case, the RF current flow emanating from the centerfeed 184 (e.g., reference numerals C₂₁ in FIG. 3C) will be uniform andthe plasma uniformity and affect of the RF standing wave will beminimized and/or removed.

In some embodiments, the center feed 184 may have a length “A” to innerdiameter ratio (e.g., diameter “D2”), or diameter aspect ratio, of atleast about 1:1. It is believed that, providing a diameter aspect ratioof at least 1:1 or longer provides for more uniform RF delivery from thecenter feed 184. In one embodiment, the inner diameter, or diameter “D2”of the center feed 184 may be as small as possible, for example, fromabout 1 inch to about 6 inches, or about 4 inches in diameter. Providinga smaller inner diameter facilitates maintaining a desired diameteraspect ratio without greatly increasing the length of the center feed184. In some configurations, for example, the center feed 184 may have alength “A” of between about 1 (25.4 mm) to about 12 inches (304.8 mm),or about 4 inches (101.6 mm).

The amount that the RF or VHF current penetrates into a conductivearticle is a function of the frequency of the current and the material'sphysical properties. Therefore, the conductivity of the material thatthe center feed 184 is made from and/or the coatings that are disposedover a surface of the center feed 184 can affect its ability todistribute the delivered RF or VHF current. In one example, the centerfeed 184 and/or conductive wall 185 are formed from an aluminum (e.g.,6061T6 aluminum) or austenitic stainless steel material. Therefore, insome embodiments, it may be desirable to define a surface area aspectratio that can be used to design a center feed 184 that has a desirableRF power delivery uniformity. The surface area aspect ratio, which isdefined as a ratio of the length “A” of the center feed 184 to thesurface area along which the RF power is configured to propagate. In oneexample, using the configuration illustrated in FIGS. 3A and 3C, theaspect ratio is the length “A” relative to the areas of the surfacesfound on diameters D₁ and D₂ (e.g., πD₁A+πD₂A) along which the RFcurrent can flow. In one example, the aspect ratio of a centrallypositioned center feed 184 is between about 0.001/mm and about 0.025/mm,such as about 0.016/mm. In another example, a centrally positionedcenter feed 184 is formed from 6061 T6 aluminum and has a surface arearatio of about 0.006/mm, where the length “A” is about 101.6 mm and thediameter “D₂” is about 25.4 mm and diameter “D₁” is about 33 mm.

It should be noted that while FIG. 3C illustrates a center feed that isannular in cross-section, this configuration is not intended to belimiting as to the scope of the invention described herein. In someembodiment, the cross-section of the center feed 184 that extendsbetween the upper surface 184A and the lower surface 184B may have asquare, hexagonal or other shaped cross-section that is able tosubstantially evenly distribute the RF power to the conductive wall 185and/or target 132. It should be noted that the upper surface 184A andthe lower surface 184B need not be parallel to each other and thus thelength “A” can be defined as the minimum distance between the uppersurface 184A and the lower surface 184B.

Magnetron Assembly

To provide efficient sputtering, a magnetron system 189 is positioned inback of the target 132 in the upper process assembly 108 to create amagnetic field in the processing region 110 adjacent the sputteringsurface 133 of the target 132. The magnetic field is created to trapelectrons and ions to thereby increase the plasma density and to therebyalso increase the sputtering rate. According to one embodiment of theinvention, the magnetron system 189 includes a source magnetron assembly420 that comprises a rotation plate 413, an outer pole 421 and an innerpole 422. The rotation plate 413 generally allows the positioning of themagnetic field generating components in the source magnetron assembly420 to be moved relative to the central axis 194 of the chamber 100.

FIGS. 4A, 4B and 4D, illustrate a source magnetron assembly 420 that ispositioned at a first radial position relative to the central axis 194,as viewed from the sputtering surface 133 side of the target 132. FIG.4C illustrates the source magnetron assembly 420 when it is positionedat a second radial position relative to the central axis 194, which isdifferent from the first radial position, and as discussed below iscreated by adjusting the rotation direction and speed. The rotationplate 413 is generally adapted to support and magnetically couple theouter pole 421 of a first magnetic polarity in the vertical directionand the inner pole 422 having a second magnetic polarity opposite tothat of the first magnetic polarity. The inner pole 422 is separatedfrom the outer pole 421 by a gap 426, and each of the poles generallycomprises one or more magnets and a pole piece 429. The magnetic fieldextending between the two poles 421, 422 creates a plasma region “P”(FIGS. 3A, 4D) adjacent a first portion of the sputtering face of thetarget 132. The plasma region “P” forms a high density plasma regionthat generally follows the shape of the gap 426.

In one embodiment, as shown in FIGS. 4A-4D, the magnetron system 189 isa non-closed loop design (e.g., open loop design) to reduce theintensity of the plasma formed in the plasma region “P” to compensatefor the use of the improved ionization potential created by the deliveryof the RF energy, from the RF source 181, to the target 132. One willnote that RF-powered plasmas are more effective in increasing theionization of atoms (e.g., gas atoms and sputtered atoms) in the plasmathan a DC-powered plasma, due to the more efficient coupling of theapplied energy to the electrons in the plasma and other electron-plasmainteraction phenomena that increase the energy of the electrons andenhance the ionization levels in the plasma.

In general, a “closed loop” magnetron configuration is formed such thatthe outer pole of the magnetron surrounds the inner pole of themagnetron forming a gap between the poles that is a continuous loop. Inthe closed loop configuration, the magnetic fields that emerge andreenter through a surface of the target form a “closed loop” pattern canbe used to confine electrons near the surface of the target in a closedpattern, which is often called a “racetrack” type pattern. A closedloop, as opposed to the open-loop, magnetron configuration is able toconfine electrons and generate a high density plasma near the sputteringsurface 133 of the target 132 to increase the sputtering yield.

In an open loop magnetron configuration, the electrons trapped betweenthe inner and outer poles will migrate, leak out and escape from theB-fields created at open ends of the magnetron, thus only holding theelectrons for a short period of time during the sputtering process dueto the reduced confinement of the electrons. However, surprisingly ithas been found that the use of an open loop magnetron configuration, asdescribed herein, provides significant step coverage improvements andprovides an improved material composition uniformity across thesubstrate surface, when used in conjunction with the RF and DCsputtering of multi-compositional targets described herein.

In one embodiment of the magnetron system 189, a rotary shaft 193Apowered by the motor 193 extends along a central axis 194 and supports aradial shifting mechanism 410, which comprises the rotation plate 413,counterweight 415 and the source magnetron assembly 420. Thereby, theradial shifting mechanism 410 moves the source magnetron assembly 420 incomplementary radial directions, such as radially towards or away fromthe central axis 194 (i.e., reference numerals “S” in FIG. 4A) as themotor 193 is rotated in different directions R₁, R₂ (FIGS. 4B, 4C).

During processing, sputtering significantly heats the target 132.Accordingly, a back region 134 is sealed to the back of the target 132and is filled with a liquid of cooling water, which is chilled by anunillustrated chiller and water piping recirculating the cooling water.The rotary shaft 193A penetrates the back chamber 100 through a rotaryseal (not shown). The magnetron system 189 including the radial shiftingmechanism 410 is immersed in the liquid disposed in the back region 134.

FIG. 4A, which is an isometric view of one embodiment of the magnetronsystem 189, generally includes a cross arm 414 fixed at its center tothe rotary shaft 193A by a clamp 414A. One end of the cross arm supportsa counterweight 415. The other end of the cross arm 414, which is acrossthe rotation axis 194 from the counterweight 415, supports a pivot 412,or rotation bearing, that is used to rotatably support the sourcemagnetron assembly 420 for rotation about an offset vertical pivot axis419. In one configuration, the pivot axis 419 is substantially parallelto the rotation axis 194. In this configuration the magnetron 420 on thecross arm 414 allows it to swing in different and complementary radialdirections with respect to the rotation center 194. The complementarymotion arises due to the center of mass of the source magnetron assembly420 being a distance from the pivot axis 419. Thus, as the cross arm 414and source magnetron assembly 420 are rotated by the motor 193, thecentripetal acceleration acting on the source magnetron assembly 420cause it to pivot about pivot axis 419 in one direction or the otherdepending on the direction that the motor 193 is turning. The center ofmass of the source magnetron assembly 420 may be defined as the centerof gravity of the source magnetron assembly 420, which may be in-boardof the inner pole 422, or closer to the rotation axis 194, for theconfiguration illustrated in FIGS. 4A-4D.

The switching between the two positions is effected by reversing thedirection of rotation of the rotary shaft 139A about the rotation axis194 and hence of the entire magnetron system 189 about the rotation axis194. As illustrated in the top plan view of FIG. 4D, when the rotaryshaft 139A rotates the cross arm 414 in the clockwise direction R₁ aboutthe rotation axis 194, the inertia and impeding forces cause the sourcemagnetron assembly 420 to rotate in the counter-clockwise directionabout the pivot axis 419 until the bumper 416 fixed to the sourcemagnetron assembly 420 engages one side of the cross arm 414. In thisprocessing configuration, or magnetron processing position, the sourcemagnetron assembly 420 is disposed at its radially outward positionclose to the edge of the target 132, so that the source magnetronassembly 420 can support a plasma for sputter deposition or sputteretching of the substrate 105. This position may be referred to as amagnetron “out” position or first position.

Alternately, as illustrated in the top plan view of FIG. 4C, when therotary shaft 193A rotates the cross arm 414 in the counter-clockwisedirection R₂ about the rotation axis 194, the inertia and impedingforces cause the source magnetron assembly 420 to rotate in a clockwisedirection about the pivot axis 419 until the bumper 417 (FIG. 4A), whichis fixed to the source magnetron assembly 420 engages the other side ofthe cross arm 414. In this configuration, the source magnetron assembly420 is disposed at its inward location away from the edge of the target132 and closer to the rotation axis 194 so that the source magnetronassembly 420 can support a plasma near the center of the target to cleanthis region. This position may be referred to as a magnetron “in”position or second position.

In some embodiments, the source magnetron assembly 420 is an unbalancedmagnetron. In one embodiment, the relative imbalance is small and thusis near a ratio of one. Typically, the imbalance is defined as the ratioof the total magnetic intensity or magnetic flux integrated over theouter pole 421 divided by the total magnetic intensity or magnetic fluxintegrated over the inner pole 422. It has been found that keeping theouter to inner field strength imbalance between about 0.5 and about 1.5the RF deposition process of multi-compositional films can be improved.In one embodiment, the outer to inner field strength imbalance is aratio of between about 18:17 and about 20:16. The magnetic imbalancecauses part of the magnetic field emanating from the outer pole 421 toproject towards the substrate 105 and guide ionized sputter particles tothe substrate 105. Because the source magnetron assembly 420 is spreadover a wide area of the target this tends to broaden the plasma region“P” and reduce its overall plasma intensity created by the delivery ofthe RF and DC power to the target 132. However, the source magnetronassembly 420 will create a higher density plasma in the plasma region“P” versus portions of the target 132 that are not directly adjacent tothe source magnetron assembly 420. As a result, the target 132 isprimarily sputtered in the area that the source magnetron assembly 420sweeps and the formed plasma causes a sizable fraction of the sputteredparticles to be ionized. The ionized particles are at least partiallyguided towards the substrate 105 by the unbalanced magnetic field.

In one embodiment, as noted above and illustrated in FIGS. 4A and 4D,the source magnetron assembly 420 is formed in a non-closed loop designto reduce the intensity of the plasma formed in the plasma region “P”.In this configuration, the non-closed loop design is formed in an arcshape that has a radius D (FIGS. 4B and 4D), which extends from the arccenter to the center of the gap 426. The arc may be sized and positionedso that the center of the radius D of the arc is coextensive with thecenter of the rotation axis 194 when it is disposed in the magnetron ina first processing position. In one embodiment, the formed arc has aradius between about 7.3 inches (185 mm) and 8.3 inches (210 mm) and thetarget 132 has a diameter of about 17.8 inches (454 mm). In oneembodiment, the arc is circular in shape and subtends an angle 441 (FIG.4D) between about 70 and about 180 degrees, such as about 130 degrees.In one embodiment, the distance from the rotation axis 194 to the pivotaxis 419 is equal to about the radius D of the arc.

In one embodiment, the outer pole 421 and inner pole 422 each comprise aplurality of magnets 423 that are positioned in an array pattern oneither side of the gap 426 and are capped by a pole piece 429 (FIG. 4A).In one configuration, the north (N) poles of the magnets 423 in theouter pole 421 are positioned away from the rotation plate 413 and south(S) poles of the magnets 423 in the inner pole 422 are positioned awayfrom the rotation plate 413. In some configurations, a magnetic yoke(not shown) is disposed between the magnets of the inner and outer polesand the rotation plate 413. In one example, the source magnetronassembly 420 comprises an outer pole 421 that has 18 magnets containedtherein and an inner pole 422 that has 17 magnets contained therein,where the magnets 423 are made from an Alnico alloy, rare-earthmaterial, or other similar material. In one embodiment, the magnets 423are each configured to create a magnetic field having a strength, at ornear their tip, of between about 1.1 kGauss and about 2.3 kGauss. In oneembodiment, the gap 426 and outer pole 421 and/or inner pole 422 areuniform in width across the formed arc. In one embodiment, the arc has awidth of about 1 to about 1.5 inches (38.1 mm).

It has been found that the uniformity of sputter deposition is improvedif the source magnetron assembly 420 is positioned on a radially outerportion of the target 132. However, if the principal sputtering isoccurring in an outer circumferential band of the target 132, some ofthe sputtered target atoms are likely to redeposit on inner portions ofthe target 132. It is believed that, since the relative sputtering rateoccurring away from the source magnetron assembly 420 is likely small,the redeposited material is likely to build up towards the rotation axis194. If the redeposited film grows sufficiently thick, it is likely toflake off and create significant particles, thereby degrading thequality of the film deposited on the substrate 105 and any devicesformed near the particles falling from the middle of the target 132.Therefore, in one configuration, as shown in FIG. 4C, the rotationdirection of the shaft 193A is changed by commands sent from thecontroller 190 to cause the source magnetron assembly 420 to pivot aboutthe pivot 412 to a position that enhances the sputtering of materialnear the center of the target 132. In one configuration the centrallypositioned magnetron assembly 420 will allow the generated plasma toextend near and/or over the center of the target 132 to remove theredeposited material disposed thereon. As further discussed below, theredeposited material on the target surface can affect the composition ofthe sputter deposited layer formed on the substrate, because of thedifference in material composition of regions of the exposed targetsurface 133 over time due to the preferential redeposition of onesputtered element versus another on regions of the target surface 133outside of the formed magnetron “race track,” or erosion grooves 916(FIG. 10B). Areas outside the “race track” generally include regionsoutside of the erosion groove(s) 916, such as the center region 918 andan outside edge region of the target 920. Sputtering of the regions thatare outside of the magnetron created erosion groove(s) 916 is much moreof an issue in RF generated plasmas versus pure DC generated plasmas dueto the increased ease in uniformly generating a plasma across the targetsurface by the delivery of RF energy to the target.

FIG. 4E illustrates an alternate embodiment of the magnetron system 189in which an outer pole 424 and an inner pole 425 form a closed loop ringmagnetron that is centered about the center “M” of the target 132. Inone embodiment, a radially symmetric shaped magnetron design is usedthat is an imbalanced and non-magnetically symmetric closed loopmagnetron design that may be useful for depositing a film using an RFand DC plasma.

In one embodiment, the magnets 423 disposed in the outer pole 424 andinner pole 425 are distributed symmetrically about a first axis 491 andasymmetrically distributed about a second axis 492. In one embodiment,the outer pole 424 and inner pole 425 have an outer to inner fieldstrength imbalance between about 0.5 and about 1.5 at a point betweenthe outer pole 424 and inner pole 425 along the first axis 491. Inanother embodiment of the imbalanced closed loop design, the imbalancebetween the outer pole 424 and inner pole 425 at a point between theouter pole 424 and inner pole 425 along the first axis 491 has a ratiobetween about 18:17 and about 20:16, outer to inner field strength. Itis noted that the magnetic field imbalance between the inner and outerpoles is different than the asymmetry of the magnets 423 relative to thesecond axis 492, since the imbalance relates to the fields createdbetween the poles and the asymmetry relates to the presence, orvariation in average magnetic field strength, at various regions acrossthe surface of the target. In this configuration, an unbalanced closedloop magnetron is used to create a ring shaped plasma region “PR” thatmay be centered about the gap 427.

The plasma density will generally be higher in the processing regionadjacent to a region of the magnetron system 189 above the second axis492 (FIG. 4E), or region having the highest density of magnets 431,versus the region of the magnetron system 189 below the second axis 492,or region having the lowest density of magnets, or no magnets. While thepole piece plates 424A, 425A coupled in the outer pole 424 and innerpole 425, respectively, are circular and are magnetically conductive,the magnetic field created between the poles along the first axis 491 inthe region below the second axis 492 will be significantly lower thanthe magnetic field created between the poles along the first axis 491 inthe region above the second axis 492.

In one example, the magnetic field strength at a point between the outerpole 424 and inner pole 425 along the first axis 491 below the secondaxis 492 is orders of magnitude less than the magnetic field strength ata point between the outer pole 424 and inner pole 425 along the firstaxis 491 above the second axis 492, or even having a magnitude of nearlyzero. In this configuration, it is believed that the electronspositioned adjacent to the less magnetized region, such as the halfsection of the below the second axis 492 shown in FIG. 4E, are betterable to escape the formed closed loop between the inner and outer poles,and thus move radially toward the target center “M”. The escapedelectrons can thus help to increase the ionization of gases near thecenter region of the target to improve target utilization. In oneembodiment, the inner diameter of the magnetron is 6.5 inches and theouter diameter is 8.3 inches. The magnetron spins on a generally centralaxis above the target and the chamber, and thus in one embodiment isconfigured to be rotated about its center “M” by the motor 193 duringprocessing.

Substrate Deposition Process Control

In one embodiment of the processing chamber 100, an impedance controller141 (FIG. 1A) is coupled between an electrode and RF ground to adjustthe bias voltage on the substrate during processing to control thedegree of bombardment on the substrate surface. In one embodiment, theelectrode is disposed adjacent to the substrate receiving surface 127 ofa support 126, and comprises the electrode 126A. In a PVD reactor,tuning of the bombardment of the substrate surface by the control of theimpedance of the electrode to ground, will affect step coverage,overhang geometry and deposited film's properties, such as grain size,film stress, crystal orientation, film density, roughness and filmcomposition. Therefore, the impedance controller 141 can thus be used toalter the deposition rate, the etching rate and even the composition ofa multi-compositional film at the substrate surface. In one embodiment,the impedance controller 141 is employed to enable or prevent depositionor etching, by the appropriate adjustment of impedance of theelectrode/substrate to ground.

FIG. 6 illustrates one embodiment of the impedance controller 141 thathas a variable capacitor tuning circuit with a feedback circuit tocontrol the properties of a deposited metal or non-metal layer on asubstrate. As discussed below, the variable capacitive tuning circuitcan be automated for a given set point during one or more parts of a PVDdeposition recipe step. The actual impedance set point can be adjustedbased on the measured current or bias voltage, or by some user definedset point, such as percentage of the full scale of the capacitance ofthe variable capacitor. The set point can depend on the desiredprocessing results to be achieved on the substrate.

Referring to FIG. 6, the impedance controller 141 can include a variablecapacitor 610, an input 616, an optional output circuit 618, an optionalinductor 620, optional resistor 621, an interface 622, a processor 624,a motor controller 626 and a motor 628. The motor 628 is preferably astepper motor that is attached to the variable capacitor 610 in a mannerto be able to vary the capacitance of the variable capacitor 610. Theaddition of an inductor 620 may be optional, and generally can beeffective to dampen or compensate for the variation in inductancecreated by having different cable lengths between the impedancecontroller 141 and the electrode 126A in different chamber setups. Theaddition of the inductor 620 may be useful to prevent the need tore-calculate the impedance control set points for every differentchamber position and configuration in the cluster tool 103.

Also, the output circuit 618 is optional, and can include a sensor todetermine the substrate bias voltage during processing. The sensor canbe a voltage sensor or a current sensor. These sensors can be used toprovide feedback to control a motor and to control the operational setpoint of the variable capacitor 610. The output circuit 618, ifincluded, can provide a feedback signal to the interface 622. Theinterface 622 provides the feedback signal to the processor 624 andcontroller 190. The processor 624 can be a dedicated electric circuit orit can also be a microprocessor or microcontroller based circuit.

The variable capacitor 610 setting is used to adjust the impedance toground and thus adjust the plasma and ion interaction with the substrateduring processing. The variable capacitor 610 is connected to the input616, which is coupled to the electrode 126A. In one embodiment, theinput 616 is coupled to the electrode 126A through one or moreadditional components, such as the optional inductor 620. In accordancewith various aspects of the present invention, it is contemplated thatother components can be provided in the circuit of FIG. 6. In oneexample, the variable capacitor 610 has a capacitance that varies frombetween about 50 picoFarads (pF) and about 1000 picoFarads (pF) and theoptional inductor 620 has an inductance of about 0.26 microhenries (μH).

The interface 622 can also receive a signal from the motor controller626. The processor 624 controls the motor controller 626 which controlsthe motor 628 in accordance with the signal and the received informationfrom the outputs of the sensors. The motor controller 626 causes themotor 628, which is preferably a stepper motor, to step through itspositions to vary the capacitance of the variable capacitor 610 as afunction of the mode control signal and of the outputs of the sensors.

In accordance with one aspect of the invention, the impedance controller141 is contained in a housing 605 that is mounted to the processingchamber 100. By mounting the impedance controller 141 to the processingchamber 100, the control of the bias voltage on substrate can be moreeasily controlled and more efficient.

The processor 624 can also be a special purpose interface circuit. Themain purpose of the interface circuit or processor 624 is to control themotor controller 626 based on the input received from a sensor, such asvoltage sensor 662 or the current sensor 663 that are attached to aportion of the circuit formed in the impedance controller 141, as justdescribed. If the processor 624 specifies a desired bias voltage setpoint, then the motor controller 626 is controlled to generate thecapacitance to achieve the set point. For example, if the processor 624is controlling the substrate bias voltage based on a measured voltage inthe impedance controller 141, then the motor controller 626 controls themotor 628 in accordance with the output of the voltage sensor 662 tomaintain a constant voltage in the circuit. In another example, if theprocessor 624 is controlling the substrate bias voltage based on ameasured current in the impedance controller 141, then the motorcontroller 626 controls the motor 628 to maintain a constant currentthrough the circuit. Any type of well known voltage sensor can be usedin accordance with the various aspects of the present invention and canbe connected between the processing chamber side of the variablecapacitor 610 and ground. Similarly, any type of well know currentsensor (not shown) can be used in accordance with the various aspects ofthe present invention. Both voltage sensors and current sensors are wellknown in the art.

Lower Process Kit and Substrate Support Assembly

Referring to FIGS. 1A and 5A, the lower process kit 165 comprises adeposition ring 502 and a cover ring 170. The deposition ring 502 isgenerally formed in an annular shape, or annular band, surrounding thesupport 126. The cover ring 170 at least partially covers a portion ofthe deposition ring 502. During processing the deposition ring 502 andthe cover ring 170 cooperate with one another to reduce formation ofsputter deposits on the peripheral edges 129 of the support 126 and theoverhanging edge 105A of the substrate 105.

The cover ring 170 encircles and at least partially covers thedeposition ring 502 to receive, and thus, shadow the deposition ring 502from the bulk of the sputtering deposits. The cover ring 170 isfabricated from a material that can resist erosion by the sputteringplasma, for example, a metallic material such as stainless steel,titanium or aluminum, or a ceramic material, such as aluminum oxide. Inone embodiment, the cover ring 170 is formed from a stainless steelmaterial. In one embodiment, a surface of the cover ring 170 is treatedwith a twin-wire aluminum arc-spray coating, such as, for example,CLEANCOAT™, to reduce particle shedding from the surface of the coverring 170. In one embodiment, the deposition ring 502 is fabricated froma dielectric material that can resist erosion by the sputtering plasma,for example, a ceramic material, such as aluminum oxide.

The cover ring 170 comprises an annular ring 510 comprising a topsurface 573 that is sloped radially inwards and encircles the support126. The top surface 573 of the annular ring 510 has an inner periphery571 and an outer periphery 516. The inner periphery 571 comprises aprojecting brim 572 which overlies the radially inward dip comprising anopen inner channel of the deposition ring 502. The projecting brim 572reduces deposition of sputtering deposits on the open inner channeldisposed between the surface 503 of the deposition ring 502 and theprojecting brim 572. The projecting brim 572 is sized, shaped, andpositioned to cooperate with and complement the arc-shaped gap 402 toform a convoluted and constricted flow path between the cover ring 170and deposition ring 502 that inhibits the flow of process deposits ontothe support 126 and the platform housing 128.

The top surface 573 may be inclined at an angle of between about 10degrees and about 20 degrees from the horizontal. The angle of the topsurface 573 of the cover ring 170 is designed to minimize the buildup ofsputter deposits nearest to the overhanging edge of the substrate 105,which would otherwise negatively impact the particle performanceobtained across the substrate 105. The cover ring may comprise anymaterial that is compatible with process chemistries such as titanium orstainless steel. In one embodiment, the cover ring 170 has an outerdiameter, that is between about 15.5 inches (39.4 cm) and about 16inches (40.6 cm). In one embodiment, the cover ring 170 has a heightbetween about 1 inch (2.5 cm) and about 1.5 inches (3.8 cm).

The space or gap 554 between the ring support portion 561 of the shield160 and the cover ring 170 forms a convoluted S-shaped pathway orlabyrinth for plasma to travel. The shape of the pathway isadvantageous, for example, because it hinders and impedes ingress ofplasma species into this region, reducing undesirable deposition ofsputtered material.

In one embodiment, as shown in FIG. 5A, the cover ring 170 is designedand positioned relative to the grounded shield 160 during processing, sothat will not be in contact with the grounded shield, and thus willelectrically “float”. Further, in one embodiment, it is desirable toposition the cover ring 170 and deposition ring 502 so that they are adistance from the substrate 105 and below the substrate receivingsurface 127 of the support 126 to allow the electric field “E” createdby the delivery of RF and/or DC power to the target 132 to be moreuniform across the surface of the substrate during processing. It isbelieved that electrically floating surfaces, such as the surfaces ofthe cover ring 170 will be subject to electron bombardment duringvarious parts of the delivered RF power's half-cycle, thus affecting theuniformity of the RF electric field in a region near the edge 105A ofthe substrate 105. Bombardment is believed to occur when the RFpotential from the power source 181A at the top surface 573 is morepositive than the average DC potential formed at the top surface 573.Therefore, in one embodiment, it is desirable to assure that thedeposited film layer formed on the upper surfaces of the cover ring 170does not have an electric path to ground and that it is disposed adistance away from the edge 105A of the substrate 105. In one example,the inner periphery 571 of the cover ring 170 is disposed a distance ofat least 0.5 inches (12.7 mm) from the edge 105A of the substrate 105.In another example, the inner periphery 571 of the cover ring 170 isdisposed a distance of between about 0.5 inches (12.7 mm) and about 3inches (76.2 mm), such as about 1 inch (25.4 mm) from the edge 105A ofthe substrate 105.

It has also been found that the placement of electrically floatingsurfaces, such as the surfaces of the cover ring 170, above the exposedsurfaces of the substrate 105, or above the substrate receiving surface127, will have an undesirable affect on the deposited film uniformityacross the substrate 105. FIG. 5B illustrates a conventional processingkit configuration in which the inner periphery 571A and top surface 573Aof a conventional cover ring 170A are positioned above the substratereceiving surface 127 and surface 105B of the substrate 105. It has beenfound in these conditions that the deposited layer tends to be thin nearthe edge of the substrate 105. It is believed that the reduceddeposition near the substrate edge 105A is created by the increaseddeposition of the ionized deposited film atoms on the top surface 573 ofthe cover ring 170, due to the increased interaction of the plasma withthe process kit surfaces disposed above the substrate surface 105B.Therefore, in one embodiment, the cover ring 170 and deposition ring 502are positioned below the substrate receiving surface 127, which as shownin FIG. 5A as being below the extension line “T”. In one embodiment, thecover ring 170 and deposition ring 502 are positioned below thesubstrate receiving surface 127 (e.g., extension line “T”) by about 0.2inches (5 mm) It should be noted that while the discussion herein andillustrations in FIGS. 1A-6 all describe the substrate receiving surface127 as being positioned below the target 132, and the cover ring 170 anddeposition ring 502 being below the substrate receiving surface 127,this vertically oriented configuration is not intended to be limiting asto the scope of the invention described herein, and is only used as areference frame to define the relative order and/or distances of each ofthe components to one another. In some embodiments, the substratereceiving surface 127 can be positioned in other orientations relativeto the target 132 (e.g., above, horizontally aligned), while the coverring 170 and deposition ring 502 are still disposed a distance furtherfrom the target 132 than the substrate receiving surface 127 is from thetarget 132.

In another embodiment, it is desirable to assure that a deposited filmlayer formed on the upper surfaces 504 of the deposition ring 502, whichis formed from a dielectric material, does not have an electric path toground to prevent the electric field in the region near the edge 105A ofthe substrate from varying over time (e.g., process a kit life). Toprevent the film layers deposited on the upper surfaces 504 from makingelectrical contact with the shield 160 and cover ring 170, theprojecting brim 572 of the cover ring 170 is sized, shaped, andpositioned to prevent the deposition on the deposition ring 502 fromforming a bridge with the layers deposited on the cover ring 170 andfrom making their way to the shield 160.

The components of the lower process kit 165 work alone and incombination to significantly reduce particle generation and strayplasmas. In comparison with existing multiple part shields, whichprovided an extended RF return path contributing to RF harmonics causingstray plasma outside the process cavity, the one piece shield describedabove reduces the RF return path thus providing improved plasmacontainment in the interior processing region. The flat base-plate ofthe one piece shield provides an additional shortened return path for RFthrough the pedestal to further reduce harmonics and stray plasma aswell as providing a landing for existing grounding hardware.

Referring to FIG. 5A, in one embodiment, the pedestal assembly 120further comprises a pedestal grounding assembly 530 that is adapted toassure that the bellows 124 are grounded during processing. If thebellows 124 achieve a different RF potential than the shield 160 it canaffect the plasma uniformity and cause arcing to occur in the processingchamber, which will affect the deposited film layer's properties,generate particles and/or affect the process uniformity. In oneembodiment, the pedestal grounding assembly 530 comprises a plate 531that contains a conductive spring 532. The conductive spring 532 andplate 531 are configured to make electrical contact with a surface ofthe shield 160 when the pedestal assembly 120 is moved to the processingposition (shown in FIG. 5A) in a direction “V” by the lift mechanism122. The conductive spring 532 may disengage from the shield 160 whenthe pedestal assembly 120 is moved to the transfer position (shown inFIG. 1A) in a direction “V” by the lift mechanism 122.

Processing Details

Embodiments of the present invention provide an apparatus and methodsfor forming integrated circuit devices, such as CMOS type integratedcircuits. However, embodiments of the invention may also be used forforming various semiconductor devices, thin-film-transistors, etc. Inone embodiment, the apparatus are adapted to perform metal depositionwhen forming a high-k/metal gate type structure, in particular whenusing a “gate last” approach. The general principles of this inventionhave been shown to apply to the deposition of various different metalsand compounds, such as tungsten (W), tungsten nitride (WN), titanium(Ti), titanium nitride (TiN), and titanium-aluminum (TiAl) alloy, HfC,HfN, silicides for FUSI, and Al. In one example, the embodimentsdisclosed herein are useful for depositing a layer comprising at leasttwo different elements, such as a titanium aluminum (TiAl) layer thathas a 50-50 alloy composition.

As device structures get smaller, especially in device formed in thesub-45 nm nodes, good film step-coverage inside an integrated circuitstructure is essential to form the various device components in afunctional semiconductor device, such as a metal gate, contact, andinterconnect features. Various methods have been used to improve PVDstep-coverage, such as long target-substrate spacing, ionized metalplasma (IMP), application of strong magnetic fields by a magnetron,re-sputtering, etc. Embodiments of the invention use a high pressureprocess, combined with RF and DC sputtering, and capacitive coupling,among others. In this configuration, which is different from IMP, the RFpower is applied directly to the target instead of a coil. The highpressure with RF power generates high density plasma near the target.

When sputtered using a high pressure with RF plasma, atoms or speciespassing through the plasma, are more easily ionized, which significantlyincreases the ion/neutral ratio. Additionally, when atoms or speciesapproach the substrate in a high pressure ambient, many collisions mayhappen which help reduce the energy of species in a vertical direction,normal to the substrate surface, and increase its movement in adirection parallel to the substrate. Also different from IMP, sincespecies get ionized near the target, and are not accelerated and/orguided by an external electromagnetic field as in an IMP process, the RFdeposition process will provide better sidewall coverage compared to anIMP type process (e.g., inductive coil). Additionally, the plasma tendsto form at a distance away from the substrate, helping to reduce plasmadamage which makes this method suitable for contact, metal gate, andother front end applications.

Embodiments of the invention include methods to improve the filmuniformity and step-coverage for this deposition process. Otheradvantages of this process may include no bottom coverage asymmetry andless bottom coverage dependency on structure size. While the descriptionbelow primarily discusses the processes of metal gate formation, thisconfiguration is not intended to be limiting as to the scope of theinvention described herein. Embodiments of the invention provide theability to deposit metals having a desirable work-function for high-kmetal gates, such as in forming MOSFET devices as previously described,particularly for the “gate replacement” or “gate last” methods. Metalshaving a desirable work-function, which are used for high-k metal gatestacks, are desirable as an alternative to adjusting threshold voltagessemiconductor devices. The work function of different materials,including metals, varies, and will be chosen based on the requirementsfor the particular semiconductor device, such as a CMOS semiconductordevice.

Additionally, embodiments provide the ability to sputter using RF energyto decrease damage on the substrate compared to traditional PVDprocesses. Embodiments also provide the ability to use the benefits ofhigh electron containment to control targeted erosion using magnets in amagnetron and DC power, and the more diffuse plasma (full-face erosion)created using an RF energy. Moreover, the embodiments provide theability to lower deposition rates for control over thin films (10 Å orless) and to sputter dielectric materials (e.g. LaOx, AlOx, etc). Otherpotential novel work function materials like TixAlyN may be controlledto achieve desired stoichiometries and work functions.

Embodiments of the invention also provide continuous path shields forgood RF containment and coherent return path in addition to a simpleform for a reduced cost manufacturing method. The low profile cover ringand deposition ring design disclosed herein allow an RF-DC PVD source tobe used in high-pressure applications that require good step coverage atvery low film non-uniformity. The substrate support includes capacitivetuning to improve the deposited film properties and film uniformity. Thevariable capacitor allows the impedance of the RF grounding path to beadjusted, so that the process uniformity for multiple recipetypes/conditions can be adjusted.

The deposition of work function metals for the replacement gateapplication for MOSFET devices such as CMOS metal gates below the 45 nmnode requires that films be deposited with good step coverage (bottomthickness/field thickness) for features with top openings from 35nanometers (nm) down to 12 nm and aspect ratios ranging from 2.5 to 5.An RF-DC PVD chamber forming “gate first” applications have typicallybeen formed at low pressures (around 2 mTorr) leading to highly uniformfilms deposited on the field region of the substrate, but not in thefeatures. These low pressure deposited films may have poor step coveragethat is on the order of 15-20%. In order to achieve the high stepcoverage, such as 75% and higher, which is desired for the “replacementgate” approach, a high pressure process may be used.

FIGS. 7A-7H illustrates cross-sections of a MOSFET transistor, such as aCMOS transistor 700 during processing. The CMOS transistor 700incorporates a gate dielectric layer, a gate metal layer, and distinctwork function metals along the gate wall such as a p-metal and ann-metal. The figures illustrate a substrate on which a gate dielectriclayer and gate metal layer are disposed. Side wall spacers are shownadjacent to the vertical sidewalls of gate dielectric layer and gatemetal layer. Embodiments of the invention may be used to form the gatestack of the MOSFET transistor shown in FIGS. 7A-7H.

FIGS. 7A-7H depict cross-sectional views of a MOSFET, such as a CMOStransistor 700 that may be formed using embodiments of the presentinvention. FIGS. 7A-7H depicts a gate last approach to forming the CMOStransistor. FIG. 7A shows a CMOS transistor 700 having a substrate 702,with a shallow trench isolation (STI) 704 formed therein according toknown methods. A high mobility interface layer 706 is formed on thesubstrate surface and over the STI 704, followed by formation of ahigh-k dielectric layer 708 on layer 706. A layer of polysilicon 710 isdeposited on the substrate and layers 706, 708 as shown in FIG. 7B. Thepolysilicon 710 undergoes a photolithography process and etch to formthe areas where the gate structures 711 will be formed, as shown in FIG.7C.

In various subsequent steps, spacers 717, salicidation 716, stressnitride layer 714, and source/drain regions 712 are formed on thesubstrate according to known methods in the art. A pre-metal dielectriclayer 718 is formed over the remaining layers and polished to thegeometry shown in FIG. 7D. The polysilcon gate structures 711 are thenetched forming trenches 720, as shown in FIG. 7E. Next, doped metalgates are deposited in the trench 720, such as a p-metal gate 723 and ann-metal gate 722, as shown in FIG. 7F. The gate structures are thenfilled with metal 724, as shown in FIG. 7G. Lastly, the substrate ispolished to form metal gates 725 on the substrate 702. Embodiments ofthe invention may be particularly useful in forming high-k metal gates,especially metal gates having metal alloys.

FIGS. 1A-6 depict various views of a RF-DC PVD chamber 100 according toembodiments of the invention. The RF-DC PVD chamber 100 allows a highpressure sputtering of thin metal films to form gate stacks, such asusing the gate last approach described in FIGS. 7A-7H. The chamberincludes an RF source with local matching network for sputtering targetmaterials using RF energy. A magnetron helps control film uniformity,and an additional DC connection to the target enhances erosion anduniformity control.

The shape of the target may also impact the plasma distribution, thusaffecting the film uniformity. Various target geometries may be usedaccording to embodiments of the invention, such as a flat, frustum, orconcave shape. Frustrum targets tend to have thicker edge and higherbump in the mid-radius. Concave targets tend to focus plasma to thecenter of the target and result in thicker center and less bump in themid-radius. In one embodiment, the target may reduce trace metalcontamination and uses a 6061Al alloy backing plate. In one embodiment,a multi-component target may be used in the processing chamber 100,wherein the multi-component target comprises a material having at leasttwo different elements disposed therein. In embodiment, themulti-compositional target is TiAl alloy target that has a 1:1, a 3:1,or a 1:3 composition ratio in various embodiments of the invention. Amulti-component TiAl target having a 1:1 ratio may have effectivebarriers to the Al fill that prevents formation of TiAl₃ at highertemperatures. If Ti and Al are deposited separately and excess Al isavailable, then TiAl₃ will form.

Multi-component targets provide a unique challenge for sputtering filmshaving the desired thickness uniformity, composition uniformity, Rsuniformity, composition ratio, step coverage, bottom coverage, overhang,etc. The different components, for example, elements in amulti-component target sputter differently based on the plasmaproperties, mass of the elements, bonding and crystal structure of theelements in the target, as well as other variables. The bombardment of amulti-component solid surface with ions and/or neutral atoms from theneighboring plasma can alter the chemical composition of the targetsurface due to the difference in the sputter yield of the differentconstituent components of the target. FIGS. 8 and 9 further illustratesome of these issues.

FIG. 8 illustrates the elastic collision, and hence scattering, ofvarious components having different masses, m1 and m2. Schematic 800illustrates a particle m2 that is stationary and the affect of acollision with another particle having a mass m1, such as an Ar+ ionfrom a plasma. Schematic 802 illustrates a collision of two movingparticles m1 and m2, and the resulting scattering of both particles dueto their collision. On a much larger scale, the general scatteringdistribution of sputtered components within a chamber, or sputterprofile, may be characterized by a cosine distribution, an under cosinedistribution, or an over cosine sputtering distribution. FIG. 9illustrates the sputtering distribution 900, or flux distribution, ofelements from a multi-component target 906. For example, in oneembodiment of the invention where the multi-component target 906 is atitanium-aluminum (TiAl) target, the sputtering distribution will bevery different for each constituent material. Aluminum is a lighter atom(mass=27) compared to titanium (mass=48) and argon (mass=40), and thuswill have a different flux distribution than titanium will have from thetarget surface.

It has been found that argon ions (Ar+) accelerated from the plasma tothe target, will collide with the aluminum atoms and form an undercosine 902 flux distribution, or sputtering distribution. In contrast,as the Ar+ ions collide with the titanium atoms in the target 906, itssputtering distribution is characterized more closely with an overcosine distribution 904. Thus, the aluminum atoms tend to travel morehorizontally than vertically compared to titanium atoms. Aluminum atomsare spread more diffusely, losing a lot more aluminum atoms to theshield rather than the substrate. However, at the center of thesubstrate, the Al is slightly higher because of the under cosinepressure profile. Thus, as pressure increases, the deposition rate needsto also increase because more scattering is going to the shield.

The unequal sputtering distribution of elements from a target causesnon-uniform composition properties of the film sputtered on a substratewithin the chamber. For example, the under cosine sputteringdistribution of aluminum may lead to high amounts of aluminum on theperipheral regions of a substrate whereas the over cosine sputteringdistribution of titanium may lead to high amounts of titanium in thecenter region of the substrate, without compensating for the unequaldistribution ratios of the two constituent components in the target 906.

Increasing pressure of the chamber also effects the scatteringdistribution of the sputtered components. Increasing the pressure willresult in more aluminum scattered due to its lower mass than titaniumand its interaction with energetic ions and neutrals in the plasma.Re-sputtering may also affect the film properties and target compositionduring processing. Atoms from the deposited film may re-sputter from thefilm to another location on the substrate or even back into theprocessing region and onto surrounding components, such as the shield ortarget. At least one challenge of a multi-compositional target is todeposit a film on a substrate having a uniform compositional ratioacross the surface of the substrate, and to achieve the overall desiredstep coverage.

Another challenge of using a multi-compositional target is the changingratio of component materials in the target over time. The chemicalcomposition of the target surface changes, forming a region known as thealtered layer. Upon initial bombardment of the surface the constituentcomponent with highest sputter yield is preferentially removed from thesurface, enriching the surface layer in the lower sputter yield materialuntil a steady state is reached. However, a non-steady state conditionmay still occur after some erosion of the target during prolonged use,leading to non-uniform composition distribution. In the example of aTiAl target, the target may shift aluminum rich because the aluminum,although easier to initially sputter from the target, may travel morehorizontally and rebound from surrounding components to redeposit on thetarget. Whereas titanium tends to move more vertically and is heavierand thus will not be scattered as much by the components in the plasma.Thus, sputtering of multi-compositional targets may also requirespecific processing steps to maintain desired and/or uniform targetsurface composition in order to achieve a desired sputtered filmcomposition.

The addition of DC power to a plasma also has an affect on the depositedfilm layer properties from a multi-compositional target. DC powercoupled to the target produces a target voltage and a correspondingsheath surrounding the target surface 133. Increasing the DC powerwidens the sheath, accelerating the Ar+ ions more and providing moreenergy to the Ar+ ions, which also affects the directionality, or fluxdistribution, of the sputtered material from the target surface (e.g.,cosine distribution). Increased DC voltage applied to the targetimproves the composition ratio of the film formed on the substratesurface because of more over-cosine like sputter distribution frommulti-component target that is thus more directed towards the substrate.More neutral deposition occurs and ion flux increases with increasedvoltage, which also helps directionality of the sputtered species. Thehigher the voltage, the more normal to the target face (i.e. the targetfirst surface) the ions are that enter target and the more normal to thetarget face the sputtering species are as they leave the target.

Increased DC target voltage sharpens, or tends to shift the fluxdistribution of the elements towards a more over cosine distribution,leading to less scattering of the sputtered species. Lower targetvoltages (e.g. 300 volts or less) tend produce a larger spread and whenincreasing DC and target voltage (e.g. to around 500 volts), the spreaddecreases and composition ratio improves, which is due at least in partto the decreased amount of scattering. As DC power is increased for afixed RF power, the ratio is coming down and approaching one. The targetpotential is going higher so the sputter angle is more normal to thesurface in both cases so both sputtering profiles tending towards moreover cosine distribution. Also, as the DC power increases, the ion toneutral ratio in an RF plasma will become lower, so increased DC voltagewill also tend to reduce the resputtering of the substrate surface dueto the application of a bias to the substrate. The increased neutralflux will generally not increase the scattering of the sputteredmaterial in the plasma.

The step coverage of a film in a feature on a substrate tends todecrease with increased DC power to the multi-component targets.Increased DC power results in higher neutral flux which means theeffective ion fraction is lower. Thus, less of the sputtered material isionized, resulting in a reduced amount of sputtered material thatreaches the bottom of the feature relative to the amount deposited inthe field. The neutral flux distribution can be considered essentiallyisotropic in energy and direction, whereas the ion flux (i.e. chargedparticles) to the substrate is accelerated through the substrate biaspotential and there has much more directed kinetic energy which resultsin the improved step coverage.

Still, even significantly higher DC power only leads to perhaps 20%decrease of step coverage. So there is still a decent amount of metalionization such that those ions are attracted to the substrate and gointo the feature. Additionally, the composition ratio of aluminum totitanium of the film deposited on the substrate also decreases withincreased DC power due to the increased vertical directionality of thesputtered material coming from the target.

In some cases, improved bottom coverage can be achieved by dropping theDC power because the film can be re-sputtered more due to theapplication of a bias to the substrate surface. However, theresputtering of the substrate surface may also be detrimental to thecomposition ratio, making it difficult to tune by just controlling theDC power. In some embodiments of the invention, a plasma is ignited byusing a DC source 182 coupled to the multi-compositional target 132.

RF power delivered to a DC powered target may decrease the targetvoltage and provide a corresponding sheath surrounding and dominatingthe DC power induced sheath. While, an RF-DC powered target has athicker plasma sheath formed below the target, and an overall highervoltage drop between the target and the plasma, the conductivity of theplasma will be increased due to the increased ion concentration in theplasma, which will make the target voltage drop at low to moderate RFpowers. Thus, an argon ion (Ar+) is accelerated even more with a thickersheath, providing a higher sputtering ion energy. In some cases, thepeak to peak voltage created by the addition of RF power will furtherincrease the ion energy of the plasma some. The thicker sheath willincrease the scattering yield. RF power increases the ionization of theplasma which helps improve the affects of substrate bias on thedepositing ions, and thus help improve step coverage of the film. Plasmaionization is also increase as RF frequency is increased, leading toincreased electron movement. The sputter yield also increases as theenergy level of the argon ions increase due to increased RF power. Whenapplying RF power to DC power, the target voltage will vary with timeand thus may be measured, for example, using a DC voltage sensor thatprovides the RMS or mean voltage value.

RF power may need to be at a minimum power to provide the ionizationlevels that improve sputtering and film properties, and in particular toimprove step coverage of the film. The RF power setting during filmdeposition may be between about 1 kW and about 3.5 kW, for example,about 2 kW. In another embodiment, the RF power setting may be about 3.2kW. Impressing an RF power on top of the DC power will change the targetvoltage, scattering, and sputter yield, which affects the compositionratio. In one embodiment, the target voltage may be between about 300volts to about 550 volts, such as about 520 volts or about 400 volts. Asthe target voltage increases, the Al:Ti ratio decreases. A higher powercreates a high power density, thus decreasing the scattering angledifference which in turned decreases the Al:Ti ratio. Also higher powerincreases the edge effect, and Rs uniformity becomes worse.

In light of the above, embodiments of the invention may include applyingDC power from a DC power source 182 coupled to the multi-compositionaltarget 132 when an RF plasma is formed in the processing region 110. Inanother embodiment of the invention, the DC power source may be set fromabout 450 W to about 2.5 kW and the RF power source may be set fromabout 1 kW to about 3.5 kW. For example, in one embodiment of theinvention, the DC power source and the RF power source are both set atabout 2 kW. In yet another embodiment of the invention, the DC powersource is set at about 2 kW and the RF power source is set at about 3.2kW. More specifically, in one embodiment if the target voltage is 320volts, the RF power is at 2 kW and the DC power is at 540 W, whichprovides good step coverage for high aspect ratio features. In anotherembodiment, the target voltage is at 500 volts and both the RF and DCpower is at 2 kW, which maintains a good composition ratio of the film.The target may be measured, for example, using a DC voltage sensor thatprovides the RMS or mean voltage value.

RF powered plasma may reach a point when argon is ionized and in turnthe sputtered metal becomes more ionized which provides improved bottomcoverage of substrate features due to the application of a substratebias. As the pressure in the processing region drops, bottom coveragealso drops, especially below 10 mTorr pressures. Lower pressures causethe composition to be more like a DC only powered plasma with an Al:Tiratio near 1:1, but decrease the step coverage. So RF power in additionto high pressure helps improve bottom coverage of features in asubstrate, especially features having high aspect ratios, where adequatebottom coverage can be very difficult to achieve.

Typical pressures in the processing region may be varied depending onthe type of multi-component target that is used, the feature size formedon the substrate and the desired film properties. The pressure of thechamber during film deposition may be between about 20 mTorr and about60 mTorr or even 75 mTorr, for example, about 22 mTorr, 30 mTorr, or 40mTorr depending on desired process effects due to the chamber pressure.In one embodiment of the invention, the Ar flow rate may be from about50 sccm to 100 sccm, for example 75 sccm. The gate valve 147 may becompletely or partially open during chamber processing.

However, increasing the pressure in the processing region too much maylead to increased scattering, especially for binary films such as TiAl.As previously discussed, aluminum and titanium scatter differently offthe multi-component target. The difference of the angular distributionarriving at the substrates may thus be modulated by adjusting parametersthat can affect the average collision frequency after the species aresputtered from the target. Increased process pressure may also lead tohigher collision frequencies, or collision times, between the sputteredspecies and the ions and electrons in the plasma and thus a widerdifference in the angular distribution for different elements. However,higher applied power from either DC or RF sources may lead to narrowangular distribution differences by providing more forward momentum forthe sputtered atoms.

Increasing the pressure in the processing region may also improve bottomcoverage. However, increasing the pressure in the processing region toomuch can also increase scattering of the sputtered species off thetarget, leading to less directionality, and thus less bottom coverage.To combat this effect of increased pressure, the target voltage may beincreased to decrease the effect of scattering of any binary components,which have different sputter yields and distributions, such as aluminumand titanium. Increasing the DC power also increases the deposition ratewhich is also helpful to combat the increased scattering effect ofhigher pressure on the system, however, the step coverage may drop somebecause the field thickness is growing faster than what is possibleinside the substrate features.

Pressure thus can help change the sputtering distribution off the targetto a preferred profile to help improve deposited film characteristics.The pressure also affects the re-distribution of sputtered species onthe target, substrate, and the shield. Higher pressures may cause thelighter compounds, such as aluminum, to redistribute to the shield andtarget in particular, thus changing the target's surface compositionalratio and decreasing the amount of aluminum that reaches the substratesurface. Increased pressure provides a greater difference in scatteringangle differences, which increases the Al:Ti composition ratio. Higherpressures also provide less edge effect, thus improving Rs uniformity.Pressure has a greater affect on improving Rs and thickness uniformitythan DC, RF, power, or capacitive tuner position, which will bediscussed in more detail below.

Pressure also affects the ionization of argon and the sputtered speciespassing through the plasma towards the substrate. Increased pressure andRF power applied to the plasma may also produce what is known as penningionization. Penning ionization is a process involving reactions betweenneutral atoms and/or molecules. In penning ionization, the interactionbetween a gas-phase excited-state atom or molecule and a target moleculeresults in formation of a radical molecular cation, and electron, and aneutral gas molecule. For example, argon atoms may ionize other argonatoms in the plasma due to penning ionization, thereby causing RF powerto more directly excite the argon plasma. The desired Argon ion energyfor the process may be between about 45 eV (electron volts) and about 70eV, such as about 50 eV. The target voltage also drops as the pressureof the processing chamber increases because the path to ground becomesmore conductive. The sheath thickness drops with increased pressurewhich affects the target voltage and the redistribution of atoms on thetarget.

A magnetron may also influence film deposition and properties. The typeand position of a magnetron will produce differing magnetic B-fields,which also affects the composition ratio of multi-compositional films.Aside from covering the target and eroding the target, positioning themagnetron above the multi-compositional target at certain locations alsohelps improve the Ti:Al ratio. Placing the magnetron in certainpositions will help prevent losing so much aluminum to the shield, whichnormally occurs due to the diffuseness of aluminum as previouslydiscussed. For example, the same sputtering profile will occur byplacing the magnetron at the center of the target, but locally if thespecies spread from the center position, completely changing where thesputtered species will spread out through the chamber. In one situation,the aluminum is also diffuse, but it's not running off to the shield,but rather it is spread over the whole area of the substrate.

In a single element uniform sputtering profile type situation, dependingon chamber geometries such as substrate spacing from the target andtarget size, the sputtering profile of the single element at any instantin time may be characterized as a single point source providing uniformcoverage over the substrate as the magnetron rotates. However, withmulti-compositional targets having two different profiles, uniformcoverage may be difficult. But when the magnetron is in the center andthe sputtering occurs mainly from the center, Rs uniformity suffers,even though the composition ratio may be improved because the sputteringsource is over the center and the sputtered species spread out prettyevenly over the substrate, resulting in a relatively even distributionover the substrate.

A closed loop magnetron confines the plasma between the B-fieldboundaries formed by the magnetron, which will depend on the exactconfiguration of magnets and type of magnets used in the magnetron. Anerosion track will develop in the target having a certain shape andlocation depending on the type of magnetron and how it's used. In a DCplasma, the magnetron confines the electrons to run around the plasmatrack and help ionize the plasma. Essentially, the magnetron helpsconfine the electrons locally so you can always supply area region whereargon is ionized close to the target surface, and thus tends to build upa target erosion track in that same area. Thus, the magnetron helpscontrol where the erosion track is formed on the target face.

An open loop magnetron creates a weaker B-field at the open endlocations, resulting in a better RF power transmitted into the plasma asa whole versus a non-magnetron containing RF sputtering processingchamber. However, for RF sputtering processes in general, a magnetron isnot necessary to sputter. The RF power itself allows power to bedelivered from the target into the electrons, which is used to ionizethe argon atoms without needing the magnetic confinement of themagnetron. Placing a closed loop magnetron closer to the target centerseemed to make the process untunable with the RF power source. Thus,confining the electrons near the center portion of the target along withRF power seems to provide little to no benefit to the sputteringprocess.

By using an open loop magnet, a full continuous closed plasma track isnot created, in other words, the electrons are trapped but only for atime, and then they can diffuse out of the magnetic field capturingregion. This is because the magnetic field created between the poles ofan open loop magnetron does not form a continuous closed-loop path whenlooking along a 2-D plane parallel to the target surface. In otherwords, tracing a path that follows portions of the formed magnetic fieldwhere the magnetic field vector is parallel to the target face (i.e.,B_(z)=0; where the z-direction is normal to the target face) along a 2-Dplane that is parallel to the target surface, the path does not form acontinuous closed loop. The film composition may depend strongly on therelative locations between the plasma erosion track and the substrateposition. The magnetron position will modulate the plasma erosion trackand adjust the film composition. For example, the magnetron position maybe in a first position, forming a plasma near an outer region of thetarget as depicted in FIG. 4D. The deposited film composition on thesubstrate may approach 1 when the magnetron is in the first position,accounting for the differing distribution profiles of the constituentelements of the target. The magnetron may be spaced above the targetfrom between about 2.2 mm to 2.8 mm, such as 2.5 mm. The magnetron mayrotate at between about 60 to about 70 rpm, such as 65 rpm.

A DC only plasma with a magnetron traps the electrons in generally amore defined region. Adding RF power essentially tunes the electrons andthe argon so that the plasma is much more highly energized even thoughthey're confined to a smaller area. The open loop magnetron permits theelectrons to escape by only partially confining them in the plasma areaunder the magnetron. The open loop magnetron may allow sputtering of alarger portion of the target surface. Thus, the magnetic field betweenthe inner and outer pole are open on one end, and electrons will leakout of the magnetic field associated with either end of the poles. Ithas been found that, placing the magnetron in the “out” position canimprove the composition ratio of the Al and Ti on the substrate surface,due to the affect of the varying sputtering distributions of themulti-component target elements. Additionally, moving the magnetron to acenter region or “in” position may be used to clean the chamber such asredeposited sputter material on the target, which will be discussed ingreater detail below with reference to FIGS. 10A-10C.

Deposited film properties may also be affected by the substrate bias. Anautomatically adjusted variable capacitive tuner may be used to providea bias to the substrate support as described above. Adjusting thecapacitance of the capacitive tuner will vary the bias voltage on thesubstrate support. Different positions of the capacitive tuner may beused to deposit and/or resputter the deposited film. In some cases, thesubstrate bias is used in an “etch mode” that incurs no net deposition,to modulate stress in a film formed on the surface of the substrate. Thesputtered metal atoms have different masses and thus by adjusting thebias voltage on the substrate one can change the deposited filmcomposition one way or another, by adjusting the ion bombardment andresputtering of the deposited film. For example, since aluminum andtitanium have different sputter yields, varying the bias voltage can beused to change how energetic the bombardment is, which will alter thecomposition ratio of the deposited film.

In one example, the higher the positive voltage on the substrate, themore titanium rich will be the deposition, since the larger, heaviertitanium atom is not as easily redirected as aluminum. Thus, underpositive substrate bias voltage, the more neutral containing titaniumatoms in the plasma tend to make it to the surface of the substrate.Whereas, aluminum is lighter and more easily ionized, and will not reachthe substrate surface due to the positive bias voltage with same degreeas titanium, leading to a titanium rich film. On the other side of thespectrum, at high negative substrate bias voltages, aluminum will movearound more than titanium because it more easily resputters by thearriving ions pulled from the plasma by the application of the substratebias. The negative voltage affects the energy of the ions that strikethe substrate surface, which will move aluminum atoms around more, alsoyielding a titanium rich surface. And since one material preferentiallyresputters at a different rate versus another, setting the substratebias voltage effectively controls the amount of resputtering, and thusthe composition ratio as well. Thus, a middle substrate bias voltagethat is not too positive or too negative is necessary to achievesubstantially uniform composition ratios of the deposited film on thesubstrate.

As the capacitance of the variable capacitor in the impedance controller141 increases, the Al:Ti ratio decreases, approaching 1, for example1.2, and even less than 1 in some conditions, such as 0.90. In oneembodiment, the Al:Ti ratio is between about 0.9 to about 1.2, such as1.0 and 1.1. The average composition ratio from center to edge may bebetween about 1.15 to about 1.16. Aluminum is easier to sputter away byAr+ ions when the bias voltage becomes negative. When the bias voltageis positive, the Al and Ti ions are pushed away from the substrate. TheAl:Ti ratio however increases because the Ti ion fraction is lower thanthe Al ion fraction in the plasma. The resonance setting of the circuitin the impedance controller 141 also affects bias voltage. As the biasvoltage approaches the resonance, the Al:Ti ratio decreases, due to thenear maximum negative substrate bias voltage achieved at the substrate.In one embodiment the voltage bias on the substrate may be from +250 to−250 V_(dc). In another embodiment, the voltage bias on the substrata isbetween about −150 volts to +50 volts.

As shown in FIG. 6, one embodiment of the invention includes adjusting abias voltage on an electrode 126A disposed in the substrate support 126that has a substrate receiving surface 127 disposed in the processingregion 110, wherein the bias voltage is adjusted by changing thecapacitance of a variable capacitor 610 to control the bias voltageachieved at the electrode 126A relative to an electrical ground. Thecapacitance of the variable capacitor 610 is varied between 5 and 1,000picofarads. For example, the variable capacitor may be set at 12.5% oftotal capacity or as high as 85% of total capacity. The resonance of thesystem may be at around 55% total capacity.

Thus, by using the various parameters discussed above, various methodsmay be used to improve step-coverage and film uniformity when using theabove apparatuses. In one embodiment of the invention, a high pressure,RF power, and DC power are used in a RF-DC PVD chamber to deposit ametal film in a gate structure.

FIG. 11 depicts a process flow of a method 1100 of depositing a thinfilm according to various embodiments of the invention. At 1102, themethod includes forming a plasma in a processing region 110 of a chamber100 as shown in FIG. 1A. The plasma is formed by using an RF powersupply 181 coupled to a multi-compositional target 132 in the chamber100, the multi-compositional target 132 has a first surface, such assputtering surface 133, that is in contact with the processing region110 of the chamber 100 and a second surface 135 that is opposite thefirst surface 133. At 1104, the method includes translating a magnetronsystem 189 relative to the multi-compositional target 132, wherein themagnetron system 189 is positioned in a first position, such as depictedin FIG. 4D, relative to a center point of the multi-compositional target132 while the magnetron system is translating and the plasma P isformed. At 1106, a multi-compositional film is deposited on a substrate105 positioned on a substrate support 126 in the chamber. Themulti-compositional film may be a metal alloy, such as a TiAl alloy,deposited in a metal gate 725, as depicted in FIGS. 7A-7H. Themulti-compositional film is deposited at 120 Å per minute and is about100 Å thick. In one embodiment, the film thickness may be between about40 Å and about 150 Å with deposition rates from about 30 Å/min. to 240Å/min. However, the desired thickness is governed by the work functionrequirement and a person of ordinary skill could adjust thataccordingly. Embodiments of the invention may be able to process morethan 20 substrates an hour.

In another embodiment of the invention, the magnetron system 189 isdisposed adjacent the second surface 135 of the multi-compositionaltarget 132 while the magnetron system 189 is translated by rotating themagnetron system 189 about the center point of the multi-compositionaltarget as illustrated in FIGS. 4B-4D. As discussed previously, themagnetron system may include an outer pole 421 comprising a plurality ofmagnets 423 and an inner pole 422 comprising a plurality of magnets 423,wherein the outer and inner poles form an open-loop magnetron assembly.In another embodiment, the method includes varying a bias voltage on asubstrate by adjusting a capacitance of a variable capacitor 610 that iscoupled between an electrode 126A disposed in the substrate support 126and an electrical ground.

The method also includes positioning a cover ring 170 a distance from anperipheral edge 129 of a substrate receiving surface 127 of thesubstrate support 126, wherein a surface of the cover ring that isexposed to the formed plasma is also disposed a distance farther awayfrom the multi-compositional target 132 than the substrate receivingsurface 127, and the cover ring 170 is not in electrical communicationwith the electrical ground when the plasma is formed in the processingregion. In another embodiment, the spacing between themulti-compositional target 132 and the substrate 105 may be between 174to 182 mm. As you move farther away from the target, the more undercosine sputtered material will hit the shield at a greater rate. Sospacing will also affect the scattering. Additionally, increased spacingmoves the substrate away from the plasma.

In another embodiment, the magnetron system may include an outer pole424 and an inner pole 425 that are concentric about a first axis 491that extends through a center point and form a closed-loop magnetronassembly such as illustrated in FIG. 4E. The plurality of magnets 423are disposed in the inner and outer poles 425, 424 and are not symmetricabout a second axis 492 that extends through the center point and isperpendicular to the first axis 491. In the embodiments of theinvention, the step coverage may be as high as 80% in high aspect ratiofeatures on a substrate. In some embodiment, the step coverage may beeven 100%.

In another embodiment, a method of depositing a thin film includesdelivering energy to a plasma formed in a processing region of achamber, wherein delivering energy comprises delivering RF power from anRF power supply to a multi-compositional target and delivering DC powerfrom a DC power supply to the multi-compositional target. Delivering DCpower means to apply a DC energy from a DC power supply, such as a DCvoltage or current to the multi-component target. Delivering RF powermeans to apply an RF energy from an RT power supply to themulti-component target.

The method also includes translating a magnetron relative to themulti-compositional target, wherein the magnetron is positioned in afirst position relative to a center point of the multi-compositionaltarget while the magnetron is translating and the plasma is formed;adjusting a bias voltage on an electrode disposed near a substratereceiving surface of a substrate support, wherein the bias voltage isadjusted by changing the capacitance of a variable capacitor to controlthe bias voltage achieved at the electrode relative to an electricalground; pressurizing the processing region to at least 20 mTorr; anddepositing a metal alloy film on a substrate disposed on the substratereceiving surface.

In another embodiment of the invention, a pre-deposition burn-in of thetarget is performed to get the preferred altered layer on the targetbefore beginning film deposition. Target burn in removes contaminantsremaining from the target manufacturing process, adsorbed gases from thetarget, and conditions the process kit to be ready for TiAl filmdeposition. Target burn in can also begin formation of the “race track”or erosion grooves in the target.

After processing a batch of substrates, the chamber may need to becleaned and the target reconditioned in particular. As previouslydiscussed, the constituent elements from the multi-compositional targetmay redeposit on the target. Aluminum is particularly susceptible toredeposit on the target center area because of its light mass and thescattering effects of the process. FIGS. 10A-10C depict a target duringvarious stages of use. FIG. 10A illustrates a new target assembly 910having a backing plate 912 and a multi-component target 914, for examplecomprising a TiAl alloy having a 1:1 ratio. After burn-in and during thefilm deposition process, the race track or erosion grooves 916 begin toform in the target. As the magnetron is rotating in the “out” positionduring sputtering, the plasma forms underneath the magnetron along anouter region of the target.

The center region 918 also experiences some erosion but not as muchsince the plasma is denser under the target in the outer region wherethe magnetron is located. Over processing time however, constituentmaterial may be redeposited on the target forming a redeposit region 919having a different composition than the rest of the target, as shown inFIG. 10C. One batch may be from 25 to 50 substrates, and the degree towhich the redeposit region 919 forms and necessitates cleaning prior tofurther film deposition will depend on the various processing settings.

A post-deposition cleaning process may be performed after processing abatch of substrates. The cleaning process may comprise a first processand a second process. The first process may include removing thesubstrate from the chamber and moving the source magnetron assembly 420to a second position. In one example, the position of the sourcemagnetron assembly 420 is adjusted by changing the rotation direction ofthe magnetron translation device (e.g., motor 193). The second positionis the “in” position as shown in FIG. 4C. A plasma P is then ignitedusing RF and DC power coupled to the multi-component target 132 and aplasma is formed under an inner portion of the first surface of themulti-compositional target. The chamber is pressurized to 2 mTorr. There-deposited material 919, which was built up on the center region 918of the target, is subsequently removed. Both the DC power and RF powerare set at 2 kW during the first process. The variable capacitor may beset at 12.5%. The plasma may remain on to clean the chamber for as longas 45 seconds. Portions of the first process, such as the plasmaignition/formation and removal, may be repeated as many as 7 times toremove the redeposit from the center of the target.

The second process includes moving the magnetron assembly to the firstposition or “out” position as shown in FIG. 4D. A plasma is ignitedusing RF and DC power coupled to the multi-component target and a plasmaformed under an outer portion of the first surface of themulti-compositional target. The chamber is pressurized to 40 mTorr andthe erosion grooves 916 are re-formed in the multi-compositional targetto look similar to FIG. 10B.

In the high pressure range of embodiments of the invention, the RF powerexcites the plasma ions, such as Ar, and the elevated pressure and Arion collisions increase the ion fraction. Heavier gases such as krypton(Kr) or xenon (Xe) may produce more effective scattering so that thehorizontal velocity of the ions may be reduced. This is especiallyuseful for heavier metal deposition such as tantalum (Ta), tungsten (W),etc. Embodiments of the invention provide the ability to achieve highfilm uniformities and step-coverage.

According to embodiments of the invention, the RF power applied to thetarget and high pressure generates a high density plasma near thetarget. When the sputtered species pass through the plasma, they getionized, which significantly increases the ion/neutral ratio of theplasma. Additionally, when the sputtered species go to the substrate ina high pressure ambient, many collisions happen which help reduce theenergy of species parallel to the substrate direction and increases itsvertical directionality. Since the atoms get ionized near the target andnot near the substrate surface (as the plasma is constrained by theasymmetric B-field from the magnetron) the velocity of the ions are notas vertical as other types of methods, such as ionized metal plasma(IMP), providing better sidewall/step coverage.

Using RF-DC power sources coupled to the multi-component target providesasymmetry and imbalance which allows the electrons to move radiallytoward the target center and plasma center thus helping to increase theionization and target utilization.

Improved step-coverage of this process may occur because of thefollowing reasons. A high density plasma forms under the target, so thatmetal species get ionized when they pass through the plasma. Highpressure and high RF power increases the RF plasma density, meaningincreased density of electrons and Ar+. High pressure also reduces themean free path so that metal species are more easily hit by electrons orAr+, and get ionized. Additionally, the sputtered metal has a lowerhorizontal velocity near the substrate surface so that the metal ion canbe easily pulled down to the substrate. The low velocity of metalspecies is achieved by losing its original velocity along the horizontaldirection through multiple random scattering with Ar+ which is furtherenhanced by high pressure. Thus, according to embodiments of theinvention, uniform film composition from multi-component targets havinggood step coverage, uniform thickness, desired constituent ratios, andRs values may be formed.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A plasma processing chamber, comprising: alid assembly, comprising: a target having a first surface that is incontact with a processing region and a second surface that is oppositethe first surface; and a lid enclosure, comprising: a center feed thatis electrically coupled to the target by a conductive wall; theconductive wall directly coupled to the center feed at a first end ofthe center feed; and the center feed including a flange at a second endof the center feed, the first end and the second end being opposing endsof the center feed, wherein the center feed is hollow throughout, thecenter feed has a length (A), the center feed has a thickness defined bya difference between an outer diameter (D₁) and an inner diameter (D₂),a surface area aspect ratio of the center feed is between about 0.001/mmand about 0.025/mm, wherein the surface area aspect ratio is calculatedby A/(πD₁A+πD₂A), the flange is directly coupled to a radio frequency(RF) power supply, and the flange is directly coupled to a directcurrent (DC) power supply.
 2. The plasma processing chamber of claim 1,further comprising a magnetron disposed adjacent to the second surfaceof the target, wherein the magnetron comprises: an outer pole comprisinga first plurality of magnets; and an inner pole comprising a secondplurality of magnets.
 3. The plasma processing chamber of claim 1,wherein the center feed is positioned over a central axis of the target.4. The plasma processing chamber of claim 1, further comprising: agrounded shield; a cover ring; and a deposition ring disposed over aportion of a substrate support, wherein during processing the cover ringis disposed on a portion of the deposition ring, and the deposition ringand the cover ring are disposed below a substrate receiving surface ofthe substrate support.
 5. The plasma processing chamber of claim 4,further comprising: a variable capacitor; and a controller that isadapted to adjust an amount of capacitance of the variable capacitorduring processing.
 6. The plasma processing chamber of claim 1, furthercomprising: a cover ring disposed below a substrate receiving surface ofa substrate support; and a motor having a shaft that has a rotationaxis.
 7. The plasma processing chamber of claim 6, further comprising: amagnetron disposed adjacent to the second surface of the target, whereinthe magnetron comprises: a cross arm that is coupled to the shaft; aplate coupled to the cross arm at a pivot point, wherein the pivot pointis a distance from the rotation axis; and an outer pole and an innerpole that are coupled to the plate.
 8. The plasma processing chamber ofclaim 7, wherein a center of mass of the plate is configured to move afirst distance from the rotation axis when rotated in a first direction,and the center of mass of the plate is configured to move a seconddistance from the rotation axis when rotated in a second direction. 9.The plasma processing chamber of claim 7, wherein a center of mass ofthe plate is configured to rotate about the pivot point in a thirddirection when the shaft is rotated in a first direction, and the centerof mass of the plate is configured to rotate in a fourth direction abouta pivot axis when the shaft is rotated in a second direction that isopposite to the first direction.
 10. The plasma processing chamber ofclaim 7, wherein the outer pole and the inner pole form a portion of anarc.
 11. A plasma processing chamber, comprising: a lid assembly,comprising: a target having a first surface that is in contact with aprocessing region and a second surface that is opposite the firstsurface; a grounded shield; and a lid enclosure, comprising: a centerfeed that is electrically coupled to the target by a conductive wall;the conductive wall directly coupled to the center feed at a first endof the center feed; and the center feed including a flange at a secondend of the center feed, the first end and the second end being opposingends of the center feed, wherein the center feed is hollow throughout,the center feed has a length (A), the center feed has a thicknessdefined by a difference between an outer diameter (D₁) and an innerdiameter (D₂), a surface area aspect ratio of the center feed is betweenabout 0.001/mm and about 0.025/mm, wherein the surface area aspect ratiois calculated by A/(πD₁A+πD₂A), the flange is directly coupled to aradio frequency (RF) power supply, and the flange is directly coupled toa direct current (DC) power supply.
 12. The plasma processing chamber ofclaim 11, further comprising a magnetron disposed adjacent to the secondsurface of the target, wherein the magnetron comprises: an outer polecomprising a first plurality of magnets; and an inner pole comprising asecond plurality of magnets.
 13. The plasma processing chamber of claim11, further comprising: a cover ring disposed below a substratereceiving surface of a substrate support.
 14. The plasma processingchamber of claim 11, further comprising: an open-loop magnetroncomprising an outer pole and an inner pole, wherein the inner pole isseparated from the outer pole by a gap.
 15. The plasma processingchamber of claim 14, wherein the open-loop magnetron further comprises arotation plate adapted to support the outer pole and the inner pole. 16.The plasma processing chamber of claim 14, wherein the inner polecomprises a first plurality of magnets and the outer pole comprises asecond plurality of magnets.
 17. The plasma processing chamber of claim11, wherein the target has a frustum or concave shape.
 18. A plasmaprocessing chamber, comprising: a lid assembly, comprising: a targethaving a first surface that is in contact with a processing region and asecond surface that is opposite the first surface; and a lid enclosure,comprising: a center feed that is electrically coupled to the target bya conductive wall; the conductive wall directly coupled to the centerfeed at a first end of the center feed; and the center feed including aflange at a second end of the center feed, the first end and the secondend being opposing ends of the center feed, and a dielectric layerdisposed over the flange, wherein the center feed is hollow throughout,the center feed has a length (A), the center feed has a thicknessdefined by a difference between an outer diameter (D₁) and an innerdiameter (D₂), a surface area aspect ratio of the center feed is betweenabout 0.001/mm and about 0.025/mm, wherein the surface area aspect ratiois calculated by A/(πD₁A+πD₂A), the flange is directly coupled to aradio frequency (RF) power supply, and the flange is directly coupled toa direct current (DC) power supply.
 19. The plasma processing chamber ofclaim 18, further comprising a magnetron disposed adjacent to the secondsurface of the target, wherein the magnetron comprises: an outer polecomprising a first plurality of magnets; and an inner pole comprising asecond plurality of magnets.